The present invention relates to devices for injecting, infusing, administering, delivering or dispensing substances, and to methods of making and using such devices. More particularly, the invention relates to a device for administering a fluid product, in particular a device for administering a fluid product at a continuous delivery rate.
For various diseases, such as for example diabetes, it can be necessary to continuously administer a particular amount of a fluid medicine to a patient. Various systems for this purpose are known, which enable the medicine to be supplied continuously over an extended period of time. The period of time of administration, the amount of the product administered within the period of time, the repetition rate of a number of consecutive administrations and possible extra deliveries can usually be set in such systems. Administering devices are known which can be connected to an external product container for a fluid medicine and, as soon as said container is empty, can be connected to the next container. Accordingly, such administering systems can be reused. Furthermore, implantable devices are also known which can be inserted into a patient's body tissue and are coupled to an external product container by means of a connector. Various possibilities exist for driving such systems, such as for example using gravity, various drive systems in the form of mechanical springs or hydraulic drives. In order to regulate the flow rate, the flow amount from the product container for the fluid medicine is usually limited at the outlet. Simple valves, clamps or programmable electronic devices can be used for this.
U.S. Pat. No. 5,788,673 discloses an infusion system in which a drive unit is combined with a conventional syringe. The syringe includes a product container that accommodates the fluid product, and a drive piston rod by which a product stopper within the product container can be advanced. The fluid product can be discharged from the syringe through an outlet opposite the product stopper. At the opening, the syringe also includes a valve for regulating the fluid flow. The drive unit comprises a chamber for a liquid medium, a second chamber which communicates with the first chamber, a piston and a valve system. A spring force can be exerted on the piston that conveys the liquid medium from the first chamber to the second chamber and back. The valve system controls the movement of the piston in the forward or backward direction and thus the discharge of the fluid product from the syringe.
The known systems for administering fluid medicines are generally designed to be reused. They therefore exhibit a complex construction comprising a large number of components and are therefore costly to manufacture. Furthermore, the patient or an assistant has to learn how to change the administering device from an empty product container to a new, full product container. If handled incorrectly, it is for example possible for an incorrect dosage to be administered to a patient.